Mechanical rabble



June 28, 1966 F, w. BROOKE MECHANICAL RABBLE 2 Sheets-Sheet 1 Filed Oct. 28, 1963 INVENTOR FRANK \N. BROOKE 77 mm BY %lllu HIS ATTORNEYS June 28, 1966 F, BR KE 3,258,256

MECHANICAL RABBLE v Filed Oct. 28, 1963 2 Sheets-Sheet 2 -l\\W7\ (2m 5 39 39 v 23 30 FIG. 5

FIG. 3

VENTOR F K W. BROOKE HIS ATTORNEYS United States Patent 3,258,256 MECHANICAL RABBLE Frank W. Brooke, King Edward Apts., Pittsburgh 13, Pa. Filed Oct. 28, 1963, Ser. No. 319,392 20 Claims. (Cl. 26634) This invention relates to a mechanical rabble for use with melting furnaces and the like. More particularly this invention relates to a semiautomatic rabble that is capable of stirring a melt, scraping slag, fishing out un- Wanted objects, adding alloying elements, and generally performing substantially all of the auxiliary functions required in connection with melting furnaces.

Accurate refining and alloying of metals requires that steps be taken to insure a proper uniform analysis. Historically, these steps have involved manual stirring or rabbling to bring about the necessary chemical refinement throughout the entire melt as well as to cause uniform mixing of alloying elements in the base material. Increase in demands for high grade steels have resulted in the development of greatly enlarged melting furnaces. The sheer volume of the material handled by such furnaces has rendered manual stirring inefficient to the point Where it is substantially ineffective.

Recently, so-called magnetic stirring has been employed in some plants in place of manual rabbling. Magnetic stirring involves elaborate and expensive equipment that creates electrically induced eddy currents in the melt, thus theoretically providing the required stirring action. Although the operation of such devices is intriguing, it has also proven to be ineffective. Such ineffectiveness can be clearly understood by recognizing the force that is necessary to move fifty tons of molten steel having a specific gravity of 7.4 and therefore being 7.4 times as sluggish as water.

In addition to being ineffective, the magnetic stirring systems in use today require bulky and expensive equipment to be located below and to the sides of the melting furnace. Thus, a rather large capital investment is subjected to the danger that the furnace might fail, dumping its load into the expensive equipment.

A seldom recognized disadvantage of magnetic stirring lies in the fact that the stirring or movement pattern is relatively uniform such that the entire melt develops a significant momentum. Such momentum makes it difficult or at least time consuming to stop the metal nfotion as required, for example, in the use of oxygen lances and also as required to permit impurities to rise from the melt into the slag layer. Radially asymmetrical mixing (as produced by manual rabbling) involves wave motions that will cause internal momentum to cancel out, thus permitting a much more rapid halting of any undesired motion.

In view of the foregoing state of the art, it has been an object of my invention to fully investigate the problems of adequate stirring and mixing in modern melting furnace installations;

Another object of my invention has been to devise a simple and inexpensive stirring mechanism or rabble that can be employed in conjunction with existing furnace installations without requiring any major modification or rebuilding of such installations;

Another important object of my invention has been to devise a versatile melting furnace stirring mechanism or rabble that can be used for adding alloying elements to the melt and for retrieving undesired impurities such as broken pieces of refractory, electrodes or other furnace elements from the melt;

A further object of my invention has been to devise a semiautomatic mechanical rabble that can perform at will, any of several useful powered motions as required 3,258,256 Patented June 28, 1966 for different stirring jobs such as mixing light alloys, or mixing heavy alloys, or for retrieving furnace parts, etc;

A further important object of my invention has been to devise a semiautomatic mechanical rabble that can be inexpensively maintained by a periodic replacement of a few easily accessible parts so as to minimize the overall expense of the equipment;

These and other objects of my invention will become more apparent to those skilled in the art on reading and understanding the following description of the inventive concept upon which my invention is based, a specific illustrative embodiment thereof, and the appended claims.

One phase of my invention relates to the use of a mechancial powered stroking mechanism that is connected to a furnace or other relatively stationary structure by a removable pivot connection. The pivot connection permits the stroking mechanism to be moved-Within a limited arc while resisting reaction forces caused by interaction of the stroking mechanism with the furnace melt. I have found that it is desirable to empoly auxiliary equipment that can be readily moved out of the way when not in use. I have also determined that adequate stirring of a large melt requires that the stirring mechanism to be moved throughout a relatively large area within the melt. The removable pivot connection of my invention permits both of these advantageous freedoms of movement while performing the basic task of anchoring the stirring mechanism while in use.

Another phase of my invention relates to the use of a stroking mechanism that has means for causing horizontal movement of a stroking arm and also includes means for causing vertical movement of the stroking arm. Preferably the stroking arm is supported so that each of the moving means can operate independently whereby a variety of independent and conjoint motions can be produced by the use of sequencing controllers that operate the two independent means.

A further phase of my invention relates to the use of a removable rabble head that is connected to the stroking arm of the mechanism by a quick release pin such as a knock-out cotter key. By making the rabble head easily removable, it is possible to live with the materials problem of finding any economical rabble head that can be immersed in the molten metal bath. Thus it is of no significance that the rabble head is gradually consumed by the bath since it can be readily replaced upon consumption. By making the rabble head readily replaceable it is also possible to increase the versatility of the stirring mechanism. For example, a specially constructed rabble head can be employed for adding predetermined quantities of alloying elements while continuously stirring the melt. This last mentioned modification is particularly important in that it permits the mechanical rabble of this invention to be employed in conjunction with the invention described in my copending application entitled Immersion Melting, Serial No. 123,687, filed July 13, 1961, now Patent No. 3,147,107. My copending application discloses, and teaches the advantages of introducing melt constituents into the molten bath below the slag layer. Where magnetic stirring is employed, such constituent introduction is clearly impossible Without substantial additional equipment. Another example of rabble head versatility is the use of specially designed rabble heads for stirring and otherwise moving the slag cover about over the surface of the melt.

A further important phase of this invention is the concept of using presently existing furnace transformers as the source of electrical power for operating the strokng mechanism. A substantial percentage of alloy meltmg 1s performed in electrical arc furnaces each of which is always provided With its own transformer. Under present practice, furnace auxiliaries such. as overhead cranes,

electrically operated trucks, etc., are powered from a central power supply thus necessitating long extension cords which clutter the floor of the shop. The mechanical rabble of my invention can easily carry its own control and receive power from its associated furnace transformer, thus minimizing the length of any electrical cable involved.

These phases of my invention are exemplified and more fully explained by the following description and the specific illustrative embodiment of my invention wherein reference is made to the accompanying drawings of which:

FIGURE 1 is a partly cross-sectional side elevational view of a furnace installation employing a mechanical rabble constructed in accordance with my invention;

FIGURE 2 is a plan view of the furnace installation shown in FIGURE 1 and taken partly in cross section along the line IIII;

FIGURE 3 is a reduced scale cross-sectional elevational view similar to FIGURE 1, but showing some of the auxiliary furnace structure;

FIGURE 4 is a cross sectional plan view of a portion of FIGURE 3 taken along line IVIV thereof;

FIGURE 5 is a partial front cross sectional view taken along line VV of FIGURE 1 showing certain internal details of the mechanical rabble;

FIGURE 6 is a side elevation view of an alternative rabble head taken along the line VIIVII of FIGURE 4; the apparatus shown in FIGURE 1;

FIGURE 7 is a cross sectional view of the modified rabble head taken along the line VIVI of FIGURE 4; and

FIGURE 8 is a cross sectional view similar to FIG- URE 7 but showing a further modification of the rabble head shown in FIGURE 5.

More specifically, in FIGURES 1 through 4 there is shown a melting furnace 10 having a basin-like metal receiving chamber or upwardly-facing concave hearth 11 and an enclosing roof 12. The furnace 10 shown is of the electric arc type and thus includes a plurality (usually three) of openings 13 in the roof 12 to permit the passage of electrodes 14 into the vicinity of the hearth 11. The electrodes 14 are supplied with a wide range of suitable voltages from an associated furnace transformer or individual power supply 15.

The furnace 10 has at least one horizontally facing servicing port or doorway 16 through which various objects can be transported to within the furnace while it is in operation. These objects might include quantities of alloying elements, chemical additives to the slag, and any equipment such as the stirrer of this invention.

Adjacent the doorway 16 there is provided a smooth floor or platform 17 that extends horizontally to support any persons or equipment that may be required in the servicing of the furnace 10. 0n the floor 17 is supported a mechanical rabble 20 that is constructed in accordance with my invention. The rabble 20 includes a main frame or base member 21 that is connected to the furnace 10 by force transmitting means such as a removable pin or pivot connection 18. The base member 21 is provided with three or more swivel casters or rollers 22 that rest upon the platform 17 and permit the base member 21 to move freely thereacross. Shown more clearly in FIG- URE 2, the combination of the pivot connection 18 and the swivel casters 22 permits the mechanical rabble 20 to move through an are that is defined by the broken lines. However, the pivot connection 18 prevents the mechanical rabble 21) from moving away from the furnace 10. r

A vertically extending frame part 23 is integrally formed with or otherwise securely connected to the base member 21 as is best shown in FIGURE 5. At its upper end, the frame part 23 carries a pair of bearing members 24 which rotatably support a shaft 25 to which a driving gear 26 is securely connected. The driving gear 26 is driven by first motor means such as an electric motor 26a. A gear housing or cradle 27 is also carried by the frame part 23 via the shaft 25 such that the cradle can pivot about an axis that is common with the axis of the driving gear 26. The cradle 27 surrounds the driving gear 26 and includes a freely rotatable idler roll 28. The idler roll 28 supports an elongated axially movable stroking member or rabble arm 29 and a slightly movable rabble arm guide frame 30.

The rabble arm 29 is constructed of an I-section-like beam that is capable of extending across at least a major portion of the hearth 11. The rabble arm 29 is substantially symmetrical about a central horizontal plane and has a pair of longitudinally extending racks or fiat gear portions 31 projecting upwardly and downwardly from the central web. As shown in FIGURE 5, only one of the racks 31 will be engaged by the driving gear 26 at any one time. Continued use of the rabble arm 29 will result in a slight vertical bending due to high temperature creep. The symmetry of the rabble arm 29 permits it to be periodically inverted to place the opposed rack 31 into engagement with the driving gear 26. In the inverted position, the additional slight amount of high temperature creep tends to restore the rabble arm 29 to its original shape.

In order to obtain vertical motion of the rabble arm 29, a lifting jack or vertical moving means 32 is pivotally connected to the rabble arm guide frame 30 at a point therealong that is displaced from the cradle 27. The lifting jack 32 is driven by an electrically energized motor 32a (see FIGURE 2). It will be seen that as the lifting jack 32 moves the guide frame 30 upwardly, the rabble arm 29 will be moved upwardly and the guide frame 30 will be required to move slightly longitudinally Within the cradle 27. The reason for the idler roll 28 is thus apparent.

The rabble arm 29 is provided at its forward end with a fork or yoke portion 33 (see FIGURE 2) that contains a pair of horizontally opposed non-circular tapered openings, slots or aligned keyhole means 34. A rabble head 40 is connected to the rabble arm 29 by a mounting portion 41 that cooperatively fits within the fork 33 and includes a non-circular opening or keyhole portion that is alignable with the slots 33. A knock-out key or cotter pin 35 fits through the slots 33 to securely retain the rabble head on the end of the rabble arm 29.

The rabble head 40 includes an intermediate downwardly extending offsetting throat portion 42 and a stirring plate or transversely-extending baflle portion 43 having a pair of generally opposed horizontally facing inclined stirring surfaces or faces 44 and 45. The inclined orientation of the faces 44 and 45 produces a particularly desirable pressure wave pattern within the melt. For example, in FIGURE 1 there is shown a melt or body of-molten metal M that is covered by a layer of slag S. A pool or agglomeration of a lightweight alloy L is suspended near the surface of the melt M and a pile or agglomeration of a heavy weight element H is settled on the bottom of the floor of the hearth 11. When the inclined baffle surfaces 44 and 45 are moved past the agglomerations of alloy elements L and H, the pressure waves and low pressure regions created will cause efficient mixing of the agglomerations with the material of the melt M.

The rabble head 40 is composed of a material (usually low carbon steel) that is usefully compatible with the metallurgical analysis of the melt M. This avoids the expense of using a high temperature material by simply permitting the rabble head 40 to be consumed gradually as it is moved about in the melt M. Replacement of the rabble head 40 is easily accomplished by withdrawing the rabble arm 29 until the slots 34 are outside of the furnace doorway 16 and knocking-out key 35 with a sledge. The key 35 is attached to the rabble arm 29 by a chain 35a. The remainder of the rabble head 40 slides down into the melt M and is consumed. A new rabble head 40 is then fastened in place by the key 35 and stirring can recommence.

Returning now to the operating mechanism mounted on open wall portion.

the base 21 there is shown a sheet metal casing 36 that encloses the driving mechanism or the horizontal and vertical moving means. The casing 36 performs several functions. It protects the operating mechanisms from the dirt and debris that are always found in foundry shops. It forms a cooling chamber that, for example, can employ coolant air from a blower or fan 37 past the various operating mechanisms and out a slot 38 adjacent the furnace end of the casing 36. The casing 36 also serves to protect workers from the gearing that might catch their clothes or working tools.

A pair of extension handles 39 are operatively connected to the base member 21 via the casing 36 to permit the machine operators to move the stirring mechanism about without danger from the rearward end of the rabble arm 29.

As shown in FIGURE 2, a sequence controller 50 for selectively controlling the horizontal and vertical move ment of the rabble arm 29, is preferably mounted on one side of the casing 36 where it is readily available to one of the machine operators. The control box 50 receives electrical power from the furnace transformer via conduits 51 and distributes the power to the electrically operated motor 32a of the lifting jack 32 and the driving gear motor 26a via electrical conduit 52 and 53, respectively. The control box 50 includes conventional sequencing control that are selectively operated by the machine operators to produce various desired motions of the rabble arm 29 and the rabble head 40. For an example, as shown in FIGURE 3, a basic stirring motion vinvolves an oblong-type stroke having a lower horizontal stroke, a curved semicircular end stroke, a return horizontal stroke that is vertically above the initial horizontal stroke and substantially parallel thereto, and a semicircular vertically downward stroke to close the oblong path. In

'order to produce this stroke by the stroking mechanism shown, the sequencing control within the controller 50 operates appropriate switch and .speed controls on the lifting jack motor 32a and the drive motor 26a to cause the following sequence; during the lowering horizontal stroke, only motor 26a is operated. The vertically upward curved stroke is produced by decelerating and reversing the motor 26' while simultaneously operating the lifting jack motor 32a to raise the rabble arm 29. During the return horizontal stroke, the motor 26a is operated continuously at a constant speed while the lifting jack 32 continues to move upwardly at a predetermined constant rate to compensate for the inherently inclined I motion of the rabble arm 29. Near the end of the return stroke the motor 26a is again decelerated and reversed I while the lifting jack motor 32a is reversed to move the rabble arm 29 downwardly.

It will be seen that by choosing various sequences of 'independent and simultaneous motions of the drive gear 26 and the lifting jack 32, various stirring patterns can be produced within the melt M.

Turning now to FIGURES 6 through 8, there is shown two alternative forms of rabble heads that are particularly useful for adding accurately measured predetermined quantities of alloying elements to the melt. In FIGURES '6 and 7, a rabble head 40 includes a downwardly offset throat portion 42 and an upper mounting portion that are each substantially identical to the corresponding portions of the rabble head 40 shown in FIGURES 1 through 4. An inclined bafiie portion 45 is formed on the rabble head 40 to create the desirable pressure wave patterns. The forward end of the rabble head 40 includes a horizontally extending channel-like section as more clearly shown in FIGURE 7. The channel-like section has a pair of vertical arms 46' that terminate adjacent their lower end in a pair of short, horizontal retaining or gripping ridges 47. The resulting structure provides a rack or chamber having a vertically-downwardly-facing The chamber is adapted to receive a thin sheet metal container 48' that is filled with a predetermined quantity of finely divided alloying elements. The chamber as shown in FIGURE 7, with the downwardly facing open portion, is adapted especially for use with alloys having a density that is less than the density of the melt M. In use the sheet metal container 48' of alloying elements is placed within the channel sections and retained by the gripping ridges 47. If desired, wedges 49' can be employed to tightly hold the container 48' in place. The rabble head 40 is then inserted into the melt M, and as it is moved through the melt, the container 48' will disintegrate, permitting the gradual agitated introduction of the finely divided alloying elements into the melt. The downwardly open orientation of the chamber prevents the light alloys from collecting along the surface of the melt thus speeding the mixing operation.

An alternative construction of the rabble head 40 is shown in FIGURE 8. In FIGURE 8 a rabble head 40" is shown as having a channel-like horizontally-extending section chamber which forms an elongated chamber similar to that of FIGURES 6 and 7. The chamber in FIGURE 8, however, has arms 46 that extend vertically and terminate at their upper ends in gripping ridges 47" to form a vertically upwardly facing open portion. A container 48" having a charge of a finely divided predetermined quantity of a high density alloying element is placed within the channel section and held by the wedges such as 49 of FIGURE 4. The operation of the rab-ble head 40 is similar to that of the rabble 40 except that the channel opening faces upwardly to prevent the settling of the heavy alloying elements.

It will be appreciated by those skilled in the art that I have devised a novel mechanical rabble that is relatively simple in construction while being versatile in operation and comparatively inexpensive to build and maintain.

While a preferred embodiment of my invention has been shown herein for purposes of illustration, it is to be understood that various changes may be made in this construction by those skilled in the art without departing from the spirit and the disclosed concepts of the invention as particularly pointed out and defined in the appended claims. Having thus described my invention, I claim:

1. A mechanical rabble for use with a melting furnace having a doorway and an upwardly-facing concave hearth, said rabble comprising: a 'base member, force transmitting means operatively connecting said base member to the furnace, an elongated rabble arm for extending into the furnace through the doorway .and across at least a major portion of the hearth, means securely mounted on said base member for moving said rabble arm in a reciprocating motion across the hearth, a rabble head that is operatively connected to said rabble arm and includes a transversely extending baffie portion for stirring a melt within the furnace, an enclosing casing mounted on said base member and substantially surrounding said moving means, and means operatively connected to said casing and employing a coolant for cooling said moving means.

2.. A mechanical rabble for use with a melting furnace having a door and an upwardly-facing concave hearth, said rabble comprising: a base member, force transmitting means operatively connecting said base member to the furnace, an elongated rabble arm for extending into the furnace through the doorway and across at least a major portion of the hearth, means securely mounted on said base member for moving said rabble arm in a reciprocating motion across the hearth, and a rabble head that is operatively connected to said rabble [arm .and includes a transversely extending bafile portion for stirring a melt within the furnace; said rabble head comprising, an elongated horizontally extending channel section having a vertically facing open portion that is bound by a pair of gripping ridges, and a thin walled container positioned within said channel section and retained by said gripping ridges; and said container having an alloying element therein for gradual dispersion into the melt.

3. A mechanical rabble as defined in claim 2 wherein said alloying element is in the form of finely divided powder.

4. A mechanical rabble as defined in claim 2 wherein said vertically facing open portion faces vertically up- Wardly and said alloying element has a density that is greater than the density of the melt.

5. A mechanical rabble as defined in claim 2 wherein said vertically facing open portion faces vertically downwardly and said alloying element has a density that is less than the density of the melt.

6. A mechanical rabble for use with a melting furnace having a doorway and an upwardly-facing concave hearth, said rabble comprising: a base member, force transmitting means operatively connecting said base member to the furnace, an elongated rabble arm having a yoke portion at one end thereof for extending into the furnace through the doorway and across at least a major portion of the hearth, said yoke portion having .aligned keyhole means formed therein, a rabble head having a transversely extending baffie portion for stirring a melt within the furnace and having a mounting portion for cooperatively engaging said yoke portion of said rabble arm, said mounting portion having keyhole means formed therein, a noncircular key extending through said keyhole means in said yoke and said rabble head mounting portion for operatively connecting said rabble head to said rabble arm, and means securely mounted on said base member for moving said rabble arm in a reciprocating motion across the hearth.

7. A mechanical rabble as defined in claim 6 wherein said rabble head is composed of a material that is usefully compatible with the metallurgical analysis of the melt.

8. A mechanical rabble for use with a melting furnace having an upwardly-facing hearth, a horizontally facing dorway, and a generally horizontal platform that is positioned adjacent to said doorway, said rabble comprising: a base member movably supported on said platform, force-transmitting means for operatively connecting said base member to the furnace to permit arcuate movement of said base member on said platform, an elongated rabble arm for extending into the furnace through the doorway and across at least a major portion of the hearth, means securely mounted on said base member for moving said rabble arm in a reciprocating motion across the hearth, and a rabble head that is operatively connected to said rabble arm and includes a transversely extending baflle portion for stirring a melt within the frunace.

9. A mechanical rabble for use with a melting furnace having a doorway and an upwardly-facing concave hearth, said rabble comprising: a base member movably supported on a platform, force-transmitting means for operatively connecting said base member to the furnace to permit arcuate movement of said base member on said platform, an elongated rabble arm for extending into the furnace through the doorway and across at least a major portion of the hearth, means securely mounted on said base member for moving said rabble arm in a reciprocating motion across the hearth, and a rabble head that is operatively connected to said rabble arm and includes a downwardly extending offsetting throat portion and a transversely-extending bafile portion that is connected to the lower end of said throat portion for immersion in a melt within the furnace.

10. A mechanical rabble for use with'a melting furnace having a doorway and an upwardly-facing concave hearth, said rabble comprising: a base member, forcetransmitting means operatively connecting said base member to the furnace, a cradle that is operatively supported on said base member, a driving gear positioned within said cradle and operatively connected to said base member for rotative movement with respect thereto, an elongated rabble arm for extending into the furnace through the doorway and across at least a major portion of the hearth, said rabble arm having a longitudinally-extending gear rack securely connected thereto, said elongated rabble arm being supportably retained within said cradle with said rack operatively engaging said driving gear, mot-or means for rotatively driving said driving gear, a rabble head operatively connected to said rabble arm and including a transversely extending baffle portion for stirring a melt within the furnace; and said rabble arm being symmetrical about .a central horizontal plane such that it includes a second gear rack that is substantially identical to the first said gear rack whereby said rabble arm can be inverted within said cradle.

11. A mechanical rabble for use with a melting furnace having a doorway and an upwardly-facing concave hearth, said rabble comprising: a base member movably supported on a platform, force-transmitting means having means removably connecting said base member directly to the furnace at a point substantially above the floor level on which the furnace is situated and for permitting arcuate movement of said base member on said platform, an elongated rabble arm for extending into the furnace through the doorway and across at least a major portion of the hearth, means mounted on said base member for moving said rabble arm in a reciprocating motion across the hearth, and a rabble head operatively connected to said rabble arm and including a transversely extending bafile portion for stirring a melt within the furnace.

12. A mechanical rabble for use with a melting furnace having a doorway and an upwardly-facing concave hearth, said rabble comprising: a base member, force transmitting means for operatively connecting said base member to the furnace, an elongated rabble arm for extending into the furnace through the doorway and across at least a major portion of the hearth, means securely mounted on said base member for moving said rabble arm in a reciprocating motion across the hearth; said moving means comprising, motor means for horizontally and vertically moving said rabble arm, and sequencecontrol means for selectively variably controlling said motor means to provide a compound two dimensional motion of said rabble arm.

=13. A mechanical rabble for use with a melting furnace having a doorway and an outwardly facing concave hearth, said rabble comprising: a base member, forcetransmitting means operatively connecting said base member to the furnace, a cradle that is operatively supported on said base member, a driving gear positioned within said cradle and operatively connected to said base member for rotative movement with respect thereto, an elongated rabble arm for extending into the furnace through the doorway and across at least a major portion of the hearth, said rabble arm having a longitudinally extending rack securely connected thereto, said elongated rabble arm being supportably retained within said cradle with said rack operatively engaging said driving gear, first motor means for rotatably driving said driving gear, a lifting jack securely connected to said base member and operatively connected to said rabble arm at a location spaced from said cradle, and second motor means for driving said lifting jack, and a rabble head that is operatively connected to said rabble arm and includes a transversely extending baffie portion for stirring the melt within a furnace.

114. A mechanical rabble as defined in claim 13 further comprising automatic control means for operating said first and second motors so as to produce a compound motion of said rabble arm comprising, two vertically spaced apart, substantially parallel horizontal strokes.

15. A mechanical rabble for use with a melting furnace having a doorway and an upwardly-facing concave hearth, said rabble comprising: a base member, force-transmitting means operatively connecting said base member to the furnace, a cradle, means connecting said cradle to said base member for supporting said cradle and permitting pivotal movement thereof about a horizontally-extending axis, a driving gear positioned Within said cradle in a coaxial relationship to the pivotal :axis thereof, means supportably connecting said driving gear to said base member and permitting rotative motion thereof about said horizontally extending axis, first motor means for driving said driving gear, a lifting jack that is securely connected to said base member at a position thereon that is spaced from said cradle, an elongated guide frame that is pivotally connected to said lifting jack at one position along its length and is movably supported by said cradle at another position along its length, second motor means for driving said lifting jack, an elongated rabble arm for extending into the furnace through the doorway and across at least a major portion of the hearth, said rabble arm being movably positioned Within said guide frame and having a longitudinally extending rack securely connected thereto that operatively engages said driving gear, and a rabble head that is operatively connected to said rabble arm and includes a transversely-extending baffle portion for stirring a melt within a furnace.

16. In a mechanical rabble for use with a melting furnace having a doorway and an upwardly facing concave hearth, a rabble head comprising a bafile portion for stirring a melt within the furnace, a horizontally extending channel section having a vertical facing open wall portion that is bounded by a pair of gripping ridges, said channel section being connected to said bafiie portion for movement therewith, a thin walled container positioned within said channel section and retained by said gripping ridges, said container having an alloying element therein for gradual dispersion into the melt.

17'. A rabble head as defined in claim 16 wherein said alloying element is in the form of finely divided powder 18. A rabble head as defined in claim 16 wherein said vertical facing open wall portion faces vertically upwardly and said alloying element has a density that is greater than the density of the melt.

19. A rabble head as defined in claim 16 wherein said vertical facing open wall portion faces vertically downwardly and said alloying element has a density that is less than the density of the melt.

20. A mechanical rabble for use with a melting furnace having an operating transformer, a doorway and an upwardly concave hearth, said rabble comprising: a base member, force-transmitting means operatively connecting said base member to the furnace, an elongated rabble arm for extending into the furnace and across at least a major portion of the hearth, electrically operated means securely mounted on said base member for moving said rabble arm in a reciprocating motion across the hearth, a rabble head that is operatively connected to said rabble arm and includes a transversely extending baffle portion for stirring a melt within the furnace, and electrical conduit means operatively connecting the furnace transformer with said electrically operated moving means.

References Cited by the Examiner UNITED STATES PATENTS 2,071,879 2/1937 Jolma 259-113 2,089,742 8/1937 Garwin 266--33 2,533,826 12/1950 Lyle 259-113 JOHN F. CAMPBELL, Primary Examiner.

WHITMORE A. WILTZ, Examiner.

M, L. FAIGUS, Assistant Examiner, 

1. A MECHANICAL RABBLE FOR USE WITH A MELTING FURNACE HAVING A DOORWAY ANS A UPWARDLY-FACING CONCAVE HEARTH, SAID RABBLE COMPRISING: A BASE MEMBER, FORCE TRANSMITTING MEANS OPERATIVELY CONNECTING SAID BASE MEMBER TO THE FURNACE, AN ELONGATED RABBLE ARM OFR EXTENDING INTO THE FURNACE THROUGH THE DOORWAY AND ACROSS AT LEAST A MAJOR PORTION OF THE HEARTH, MEANS SECURELY MOUNTED ON SAID BASE MEMBER FOR MOVING SAID RABBLE ARM IN A RECIPROCATING MOTION ACROSS THE HEARTH, A RABBLE HEAD THAT IS OPERATIVELY CONNECTED TO SAID RABBLE ARM AND INCLUDES A TRANSVERSELY EXTENDING BAFFLE PORTION FOR STIRRING A MELT WITHIN THE FURNACE, AN ENCLOSING CASING MOUNTED ON SAID BASE MEMBER AND SUBSTANTIALLY SURROUNDING SAID MOVING MEANS, AND MEANS OPERATIVELY CONNECTED TO SAID CASING AND EMPLOYING A COOLANT FOR COOLING SAID MOVING MEANS. 